Method for refining metals and alloys with a manganese-germanium treating agent



Eet. 119, 1967 Yukfb ICHINOSE METHOD FOR REFINING METALS AND ALLOYS WITH A MANGANESE-GERMANIUM TREATING AGENT Filed March 8, 1965 Degree or vacuum (mm Hg) fem 07 r /0 per u e Mn added 3 Me/f dam/r7 2 Ge added C057. /0 k I I 1 Degree of 5 vacuum Pam/er mpuz azea aeaea/aa/ee/aa/ea 777'ne (m/h) w uklo I 3 Sheets-Sheet 1 du nose.

INVENTOR ATTORNEY p 19, 1967 I YUKIO ICHINOSE 3,342,589

METHOD FOR REFINING METALS AND ALLOYS WITH A MANGANESE-GERMANIUM TREATING AGENT Filed March 8, 1965 "'5 Sheets -Sheet 2 mmmemare/ (b)/0m/'nufes affer mew-down offer melf-d0wn C) /0 m/hufes affer (CU/0 m/hufes affer adm'f/bn of Mn add/flan of Ge Yuk/' Iakhofa INVENTOR BY @Zi 2- dwf ATTORNEY $et, l

YUKIO ICHINOSE Filed March 8, 1965 Number of mc/us/oos Number or /'no/us/'ons 3 Sheets-Sheet 3 F76. 3 D/amefer of non-mefa/l/o/ho/us/ons (m/cron) 05% Mn added O.5%Mn+ /%6e 2500 added Tofa/number 2000 of/hc/us/one 7% w 500 490mm? =52oo/mm g E /000 g 500 Q 1 Be/ovv Above Be/ow Above (25%Mn+ 2%Ge Q5%Mn+ 4%6e 2500 added added 2000 Tom/number Tofa/number OfmC/US/Ons of fno/ue/one /500 300/07/77 5 70 2 (\I E /000 E 500 S Be/ovv Above buovv Above /.0% Ge added (3 F? 2000 Tofo/ number 15 600 of/hc/usl'ons 3900/mm E /000 Q E g 500 R Q 0.5 2 3 Be/ow Above INVENTOR BY QM ATTORNEY United States Patent 3,342,582 METHOD FOR REFINING METALS AND ALLOYS WITH A MANGANESE-GER- MANIUM TREATING AGENT Yukio Ichinose, Koknbnnji-shi, Japan,

Hitachi, Ltd., Tokyo, Japan Filed Mar. 8, 1965, Ser. No. 437,955 Claims priority, application Japan, Mar. 11, 1964, 39/ 13,340 5 Claims. (Cl. 75 49) The present invention relates to a method of refining metals and alloys and more particularly to an improvement in the method of refining for use in combination with the vacuum melting of metals and alloys.

In the vacuum melting of iron and its alloys, nickel and its alloys, and the like, these metals and alloys have hitherto been refined by a refining agent such as manganese or a manganese-silicon alloy. It is considered that the mechanism of refining involved in the refining ofthese metals and alloys by the above-described refining agent is effected not only by a getter action by the same. Or more precisely, when manganese is added to a metal being molten in a vacuum for the purpose of refining, the pressure of the melting atmosphere abruptly decreases immediately after the manganese is addedto the metal, and such abrupt pressure drop is caused by a getter action of vaporized manganese. Assume now that the concentration of dissolved gas is determined in accordance with Sieverts law,

then the gas concentration Cg can be expressed as where, k is a constant and p is the pressure of the melting atmosphere. This means that the concentration of dissolved -gas in the melt decreases with the decrease in the pressure of the melting atmosphere and the above-described defining action can thus be effected. On the other hand, a portion of manganese added to the metal melt acts to reduce oxides in the melt and is consumed by conversion into'an oxide of manganese or MnO. But this is undesirable from the viewpoint of satisfactory refining because manganese in the form of MnO provides a cause of nonmetallic inclusion in the metal.

Therefore, it is the primaIycbject of the present invention to provide an improved method for refining metals and alloys which is completely free from the above-described defect encountered with the prior method in which manganese is solely used as the refining agent.

According to the present invention, there is provided a method for refining metals and alloys for use in combination with the vacuum melting thereof, comprising melting the metal or the alloy in a vacuum and adding to the melt a refining agent consisting of manganese and germanium.

There are other objects and particularities of the present invention which will become obvious from the following description with reference to the accompanying drawings, in which:

FIG. 1 is a graphic illustration of the process of refining of an alloy in an experiment made according to the method embodying the present invention;

FIG. 2 is a schematic illustration of successive changes in an amount of slag on the melt surface observed in the experiment shown in FIG. 1; and

FIG. 3 is a graphic illustration of the distribution of non-metallic inclusions in plate-like solid masses of an alloy refined by the method according to the present invention.

The inventor has discovered that the simultaneous addition of manganese and germanium to a melt of a metal or an alloy during its vacuum melting is remarkably efassignor to fective in that the deoxidizing action of the manganese is promoted by the simultaneous presence of the germanium and the refining effect on the melt thus attained is far greater than when one of these elements alone is added to the melt. The mechanism of refining by these elements will be discussed in detail hereinbelow. When manganese is added to an alloy consisting, for example, of iron and nickel, a portion of the manganese acts to reduce oxides of iron and nickel because manganese has a higher atfinity for combining with oxygen than iron and nickel. Thus, manganese turns into the form of MnO and remains as slag on the melt and as a non-metallic inclusion in the melt. Or more precisely, a portion of the manganese added to the melt is consumed by conversion into a reduction product in the form of MnO, but the presence of the reaction product in the form of MnO is undesirable because it provides a cause of non-metallic inclusion in the alloy. On the other hand, germanium acts as a reducing agent for such MnO and the germanium itself is converted into the form of GeO, which is highly evaporative and is discharged in the form of a gas at high temperatures. In other words, a reversible chemical reaction,

MnO (liquid)+Ge (liquid):Mn (gas)+GeO (gas) occurs and proceeds in the direction of the upper arrow or in the right-hand direction and is promoted.

It will be understood that the joint use of manganese thus the refining action and germanium as a refining agent for use with vacuum.

melting of a metal or an alloy is so effective that the refining action by these elements through the above-described refining mechanism can greatly improve the mechanical or physical properties of the metal or alloy.

In FIG. 1, there is shown a process of heating and melting of an iron-nickel alloy when the method accord on the melt surface during the melting process in the experiment shown in FIG. 1. In FIG. 2, reference numerals 1, 2 and 3 designate a crucible, melt surface and slag on the melt surface, respectively. In (a) of FIG. 2, it will be seen that a considerable amount of slag 3 is still present on the melt surface 2 immediately after melt-down. In 10 minutes after melt-down, the slag 3 is slightly forced towards the periphery of the crucible 1 due to the boiling action of the melt as shown in (b) of FIG. 2. Then when manganese is added to the melt, the slag 3 is further forced towards the periphery of the crucible 1 by the boiling action due to evaporation of the manganese, but is still present on the melt surface 2 as shown in (c) of FIG. 2. By the subsequent addition of germanium to the melt, the slag 3 completely disappears, as shown in (d) of FIG. 3, due to the reducing action by the germanium and the evaporation of GeO formed by the reduction of the slag. This means that the refining action has completely been effected.

The following table shows comparative values, in percent by weight, of the raw material composition of ironnickel alloys and the final composition as determined by chemical analysis of ingots of the iron-nickel alloys to which manganese alone, both manganese and germanium, and germanium alone are added in various percentages during the vacuum melting of the alloys.

Raw material composition (percent) Composition determined by analysis (percent) Refining additive Fe Ni Ge Mn Fe Ni Ge Mn 0.5% Mn 57. 7 41. 8 0.5 57. 41. 4 0.45 57. 1 41. 4 1.0 0.5 58. 1 41. 2 0. 8 0. 1 56. 5 40. 9 2.0 0. 5 55. 9 40. 6 1. 5 0.2 55. 4 40.1 4.0 0.5 54. 8 40. 5 3i 1 0.3 49. 3 49. 8 0. 5 Balance 48. 7 0. 23 49. 2 49. 3 1. 0 0.5 Balance 48. 4 0. 7 0. 48. 7 48.8 27 0 0.5 Balance 47.9 1. 7 0. 14 47.7 47.8 4.0 0. 5 Balance 47.3 3. 4 0v 12 1.0% Ge 49. 5 49. 5 1.0 Balance 49.1 0.8

- From this table, it will be seen that the amount of.

manganese consumption is small when manganese alone is added to the alloy melt, while the amount of manganese consumption is quite large when both manganese and germanium are added to the melt. This is considered to be attributable to the fact that MnO is reduced to manganese by the action of germanium and such manganese is evaporated away from the melt.

' FIG. 3 shows the distribution of non-metallic inclusions, as examined by an electron microscope, in plate-like masses machined from the ingots of an ironnickel alloy to which manganese alone, both manganese and germanium, and germanium alone are added in various percentages during the vacuum melting of the alloy. From FIG. 3, it will be seen that the amount of non-metallic inclusions is less with the simultaneous addition of manganese and germanium than with the sole addition of either manganese or germanium. The amount of nonmetallic inclusions is especially small with the joint addition of 0.5% manganese and 4% germanium, or of the order of one third the amount when manganese is added alone. According to the results of examinations on the recrystallized structure of the iron-nickel alloy by means of a microscope, greater crystal grains and less non-metallic inclusions can be obtained by the joint addition of manganese and germanium as compared with the sole addition of manganese.

Although the principle of the invention has been described in detail with regard to a case in which it is applied to vacuum melting of an iron-nickel alloy, it will be readily apparent that the present invention is applicable to other metals and alloys such as an iron-cobalt alloy and a nickel-cobalt alloy whose metal oxides can easily be reduced by manganese and germanium. Therefore, it will be apparent that a metal or alloy material thus obtained has remarkably improved mechanical or physical properties.

What is claimed is:

1. A method for refining metals and alloys for use in combination with the vacuum melting thereof, comprising melting the metal or alloy in a vacuum and adding to the melt at refining agent consisting of manganese and germanium.

' 2. A method according to claim 1, in which said man: ganese is added in the form of a manganese alloy.

3. A method according to claim 1, in which said germanium is added in the form of a germanium alloy.

4. A method according to claim 1, in which said manganese and germanium are added in the form of an alloy containing manganese and germanium therein.

5. A method according to claim 1, in which said metals are iron, nickel, cobalt and alloys of these metals.

References Cited Vacuum Metallurgy, papers presented at the Vacuum Metallurgy Symposium of the Electrothermics and Metallurgy Division of the Electrochemical Society, Oct. 6 and 7, 1954, Boston, Mass, ed., by John M. Blocher, Jr. 1955).

HYLAND BIZOT, Primary Examiner.

DAVID R. RECK, Examiner. H. W. TARRING, Assistant Examiner. 

1. A METHOD FOR REFINING METALS AND ALLOYS FOR USE IN COMBINATION WITH THE VACUUM MELTING THEREOF, COMPRISING MELTING THE METAL OR ALLOY IN A VACUUM AND ADDING TO THE MELT A REFINING AGENT CONSISTING OF MANGANESE AND GERMANIUM. 